Charles v



C. V. LOGWOOD & C. F. ELWELL.

SPACE TELEGRAPHY. APPLICATION 11150 JUNE 12. 1911'.

l 1 95,485. Patented Aug. 22, 1916.

N/TNES$ES-' INVEN O FS 1 cKLoGu/Ooo c.,=: EL MEL.

sna es PATENT JHARLES V. LOGWOOD AND GYRIL F. LELWELL, OF PALO ALTO, CALIFORNIA.

SPACE TELEGBAPHY.

Specification of Letters Patent.

llatcntcd'fiug. 22, 1016.

T 0 all whom it may concern:

Be it known that we, CHARLES V. Loowoon and CvIuL F. ELWELL, citizens of the United States, and residents of Palo Alto, in the county of Santa Clara and State of California, have invented certain new and useful Improvements in Space Telegraph of which the following is a specification.

The invention relates to space telegraphy and especially to transmitting systems therefor, wherein the signal is transmitted through the natural media by means of continuous undamped waves of a high frequency.

The object of the invention is to provide means for signaling with continuous waves having a. frequency higher than the limit of audibility without the use of some special device at the receiving station for reducing the frequency to within the range of audi bility.

Another object of the invention is to break up the high frequency wave train into groups having a group frequency within the range of audioility.

Another object of the invention is to provide means for overcoming .the effects of static or atmospheric electricity.

' This invention relates to an improvement in the loulsen system of space telegraphy. Such system is the only system to our knowledge which employs a continuous undamped wave of very high frequency, and in such system a ticker or interrupter is employed at the receiving station in order that the signals may be received. A receiving station not equipped with aticker cannot re- .ceive messages transmitted by the Poulsen sending station unless the sending station is equipped with an interrupter and this feature is extremely detrimental when in times of distress it is necessary to communicate with every wireless receiving station, r gardless of whether it is equipped to receive continuous undamped waves or damped waves of the spark system. In order to overcome this difficulty, we arrange an interrupterin the Poulsen sending circuit which breaks the continuous waves into groups, the group frequency being such that the messages may be received by receiving stations equipped to operate on the spark sys tem.

The effect of this invention is to produce a high piercing note at the receiving station which will drown out the note produced by atmospheric or static charges.

For the purpose of explaining the inven- 4 tion, we have shown diagrammatically in the accompanying drawings, several forms of connecting up the transmitting apparatus, but it is to be understood that our in vention is not to be limited to such forms, as changes may be made in the position of the various elements without varying from the spirit of our invention.

The drawing shows a. source of continuous oscillations, directly connected to the antenna, the interrupter being arranged in series with the sending key, which is shunted on part of the inductance.

The source of continuous undamped oscillations is shown as an arc circuit, having a capacity 2 in shunt on the are 3. Currcnt is supplied to the are 3 by means of the wires 4-5 which emanate from the source of power.

When the antenna is directly connected to the are circuit, the connection to earth E is made from one side of the'arc.

The interrupter 8 may be of any suitable form, and in the drawings we have shown a rotatable connnutator, which is rotated by any desirable means at a rate to cause a frequency within the limits of audibility.

Arranged between the source of oscillations and the antennais a variable inductance 9. Shunting a portion of the induc-' tem' receivers are effected only by the group frequency, regardless of the frequency of the high frequency oscillations forming said groups.

The frequency of the continuous oscillations is in excess of 100,000 per second and we find that a group frequency between 500 and 1000 produces efficient results.

When it is desirable to communicate only with stations which are associated with the sending station and which are equipped to receive high frequency continuous oscillations, the interrupter may be cut out and the signals transmitted without breaking the oscillations into groups.

We claim Tn ntrunsniission system for space telegmpliy, source of continuous undnmped oscillations, a conductor connecting one side of said source to earth, an antenna connected to the other slde of said source, an lnducof said inductance and a key and interrupter in said shunt circuit.

- CHARLES v. Loevvoon.

CYRIL F. ELWELL.

' Witnesses: 1

H. G. Pnos'r, P. S. PIDWELL. 

